Amy

"You can have your sister, Dad. I'll take Amy." Your dad smiles at you.

"You're such a good kid. Come on Grace, it'll be just like that time I helped you move in college."

Grace smiles and rolls her eyes, "I was never able to wash the cum stains out of my favorite pair of pants. You ruined them without a second thought." She pushes Greg back into his seat and starts expertly gyrating her hips onto her brother. You watch her large ass for a bit before turning to the one about to be in your lap.

Amy is standing in front of you awkwardly. "Is everything alright?" you ask her.

"It's just, I've never done this before," she stammers out.

"No problem," you tell her, "just copy your mom." She bites her lip and nods, studying her mother as she grinds her ass into her uncle. After a bit of watching, she turns around and does her best to imitate her mom. If it wasn't for her ass being so spectacular, you wouldn't be turned on at all. You allow her to awkwardly shuffle around in your lap for a while, watching Greg shoot a massive load all over his sister's ass, before finally stopping her.